a jet leaves the Charlotte, North Carolina, airport traveling at an average rate of 564 km/h. Another jet leaves the airport one half hour later traveling 722 km/h in the same direction. How long will the second jet take to overtake the first?

Answer 1

let time of 1st jet be t hrs
then time of 2nd jet = t-1/2 hrs

distance of 1st = 564t
distance of 2nd = 722(t-1/2) = 722t - 361
but they went the same distance, so ...
564t = 722t - 361
-158t = -361
t = 2.285 hrs

so the 2nd takes 2.285 - .5 hrs
= 1.785 hrs or 1 hour and 47 minutes